Susac's syndrome
Encyclopedia
Susac's syndrome is a microangiopathy characterized by encephalopathy
, branch retinal artery occlusions and hearing loss. It is caused by the immune system attacking healthy tissue, and can lead to mental disorders.
Susac's Syndrome usually affects women around the age of 30 years old, with female to male ratio of cases of 5:1.
(MS) and acute disseminated encephalomyelitis
(ADEM) can mimic the MRI changes seen in patients with Susac's syndrome. However, the callosal lesions in Susac's syndrome are centrally located. In comparison, patients with MS and ADEM typically have lesions involving the undersurface of the corpus callosum. Deep gray matter involvement commonly occurs in ADEM but is very rare in MS. Leptomemingeal involvement is not typical of either MS or ADEM.
In what are believed to be many cases, Susac's syndrome is not diagnosed for many years because so many of the usual tests are absolutely normal.
There are a few reported cases of Susac's Syndrome-related retinopathy responding to hyperbaric oxygen therapy
, with significant improvement of acuity. There is another report of the syndrome recurring after 18 years. Treatment regimens proposed empirically include IVIG and high-dose intravenous steroids. It is generally agreed that some method of immunosuppression is necessary, at least at the initial onset of the syndrome. A recent paper from Vanderbilt University Medical Center confirmed that "immunosuppression is the mainstay of Susac’s syndrome treatment."
Dr. William Hoyt, M.D., neuroopthalmologist at UCSF who gave the syndrome the name Susac's, compared it to a "storm going through."
Proposed causes include autoimmune vasculitis, hypercoagulable state and viral infection. Evidence for viral infection includes a prodromal illness in some patients. Development of symptoms during pregnancy and oral contraceptive use suggest a possible contribution of coagulation abnormalities in such patients. However, the relatively infrequent recognition of this syndrome has provided few cases for systematic study of possible causative factors.
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...
, branch retinal artery occlusions and hearing loss. It is caused by the immune system attacking healthy tissue, and can lead to mental disorders.
Description
Susac's Syndrome is named after Dr John Susac, of Winter Haven, FL, who first described it in 1979.. Susac's syndrome is a very rare disease, of still unknown etiology, and many persons who experience it do not display the bizarre symptoms named here. Some sufferers often experience a personality change and develop bizarre and paranoid behavior. Their speech can be affected, and many experience unrelenting and intense headaches and migraines, some form of hearing loss, and impaired vision. The problem usually corrects itself, but this can take up to five years. In some cases, subjects can become confused, and believe they are re-living a time from their remembered past. According to Michael Hahn, a US Expert on the subject, the delusion of living in a foreign country occurs in a "fair percentage" of cases.Susac's Syndrome usually affects women around the age of 30 years old, with female to male ratio of cases of 5:1.
Diagnosis
Radiographic Appearance: In a recent analysis (Susac et al., 2003), MRI images from 15 patients fulfilling the diagnostic criteria of Susac's syndrome were reviewed. Multifocal supratentorial lesions were present in all patients. Most lesions were small (3 to 7 mm), though some were larger than 7 mm. All 15 patients had corpus callosum lesions. These all had a punched-out appearance on follow up MRI. Though most commonly involving white matter, many patients also had lesions in deep grey matter structures (9 of 15), as well as leptomeningeal enhancement (9 of 15). Multiple sclerosisMultiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
(MS) and acute disseminated encephalomyelitis
Acute disseminated encephalomyelitis
Acute disseminated encephalomyelitis is an immune mediated disease of the brain. It usually occurs following a viral infection but may appear following vaccination, bacterial or parasitic infection, or even appear spontaneously. As it involves autoimmune demyelination, it is similar to multiple...
(ADEM) can mimic the MRI changes seen in patients with Susac's syndrome. However, the callosal lesions in Susac's syndrome are centrally located. In comparison, patients with MS and ADEM typically have lesions involving the undersurface of the corpus callosum. Deep gray matter involvement commonly occurs in ADEM but is very rare in MS. Leptomemingeal involvement is not typical of either MS or ADEM.
In what are believed to be many cases, Susac's syndrome is not diagnosed for many years because so many of the usual tests are absolutely normal.
Treatment
None of the treatments has been scientifically confirmed. All are speculative. Some of the treatments have side effects that the patient does not need to suffer. Many with Susac's syndrome improve with no treatment.There are a few reported cases of Susac's Syndrome-related retinopathy responding to hyperbaric oxygen therapy
Hyperbaric oxygen therapy
Hyperbaric medicine, also known as hyperbaric oxygen therapy , is the medical use of oxygen at a level higher than atmospheric pressure. The equipment required consists of a pressure chamber, which may be of rigid or flexible construction, and a means of delivering 100% oxygen...
, with significant improvement of acuity. There is another report of the syndrome recurring after 18 years. Treatment regimens proposed empirically include IVIG and high-dose intravenous steroids. It is generally agreed that some method of immunosuppression is necessary, at least at the initial onset of the syndrome. A recent paper from Vanderbilt University Medical Center confirmed that "immunosuppression is the mainstay of Susac’s syndrome treatment."
Dr. William Hoyt, M.D., neuroopthalmologist at UCSF who gave the syndrome the name Susac's, compared it to a "storm going through."
Pathogenesis
In the March 1979 report in Neurology, Drs. Susac, Hardman and Selhorst reported two patients with the triad of encephalopathy, hearing loss and microangiopathy of the retina. The first patient underwent brain biopsy, which revealed sclerosis of the media and adventitia of small pial and cortical vessels, suggestive of a healed angiitis. Both patients underwent fluorescein retinal angiography that demonstrated multifocal retinal artery occlusions without evidence of embolic disease. Though the exact pathogenesis of this disorder is unknown, the findings of retinal microangiopathy and brain biopsies suggest a small vessel vasculitis leading to arteriolar occlusion and microinfarction of cerebral, retinal and cochlear tissue. Demyelination is not a typical feature of Susac's syndrome. Muscle biopsies from such patients are usually normal, but some have also shown nonspecific signs of inflammation such as dense hyaline material surrounding endomysial capillaries. This suggests a possible systemic component of this disease, despite the predominance of central nervous system features.Proposed causes include autoimmune vasculitis, hypercoagulable state and viral infection. Evidence for viral infection includes a prodromal illness in some patients. Development of symptoms during pregnancy and oral contraceptive use suggest a possible contribution of coagulation abnormalities in such patients. However, the relatively infrequent recognition of this syndrome has provided few cases for systematic study of possible causative factors.